This invention relates to a process for producing decachlorooctahydro-1,3,4-metheno-2H-cyclobuta(c,d)-pentalen-2-one, hereinafter referred to as C.sub.10 Cl.sub.10 O. C.sub.10 Cl.sub.10 O is a complex chlorinated polycyclic ketone having a molecular weight of 490.68. It is believed to be most accurately represented by the following cage structural formula: ##SPC1##
In U.S. Reissue Pat. No. 24,435 of Everett E. Gilbert and Silvio L. Giolito granted Feb. 25, 1958, (original U.S. Pat. No. 2,616,928 dated Nov. 4, 1952) there is described a process for preparing a biocidally active C.sub.10 Cl.sub.10 O ketone and its hydrates by reacting hexachlorocyclopentadiene and sulfur trioxide at temperatures in the range of about 35.degree.C. to about 70.degree.C. to form a reaction product thereof and hydrolyzing the resulting reaction product.
The above ketone product has proved to be of outstanding value in numerous biocidal applications, particularly in the control of ants, roaches and other resistant pests.
The original preparative process of the above reissue patent, while quite satisfactory in most respects often resulted in low yields of ketone product or required long reaction times to produce desired yields, and such long reaction times tended to produce a degraded product, particularly with respect to color and the presence of impurities including inorganic (methanol insoluble) impurities.
More recently, it has been suggested in U.S. Pat. No. 3,333,003 of R. J. DuBois, granted July 25, 1967, to produce C.sub.10 Cl.sub.10 O by reacting hexachlorocyclopentadiene and sulfur trioxide at temperatures between 35.degree.C. and 90.degree.C. using an antimony compound as catalyst, and hydrolyzing the reaction product. However, in commercial use of this prior process, serious problems were encountered because of the formation of a toxic aqueous waste stream which tended to pollute the environment.
Under this prior process, the yield of the C.sub.10 Cl.sub.10 O, in particular the purified C.sub.10 Cl.sub.10 O, generally was in the range 80-90%; however, in order to obtain a yield of about 90% a reaction time of 2-4 hours or more was necessary. Furthermore, the C.sub.10 Cl.sub.10 O product was relatively impure. Obviously, it is desirable to prepare a product of high assay, which is generally indicated by infrared assay. Methanol insolubles indicate presence of inorganic impurities.
Accordingly, it is an object of this invention to produce C.sub.10 Cl.sub.10 O by a process which results in a high yield.
It is another object of this invention to produce C.sub.10 Cl.sub.10 O in high yield without formation of a toxic aqueous waste stream.
It is another object of this invention to produce C.sub.10 Cl.sub.10 O of good quality and high yield.
It is an additional object of this invention to produce C.sub.10 Cl.sub.10 O at relatively high temperatures whereby reaction time is substantially decreased over prior art processes.